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368 results on '"Saint-Girons, G."'

1. Giant Tuning of Electronic and Thermoelectric Properties by Epitaxial Strain in p-Type Sr-Doped LaCrO3 Transparent Thin Films

Author

Han, D., Moalla, R., Fina, I., Giordano, V. M., d'Esperonnat, M., Botella, C., Grenet, G., Debord, R., Pailhes, S., Saint-Girons, G., and Bachelet, R.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons, Physics - Applied Physics
Abstract

The impact of epitaxial strain on the structural, electronic, and thermoelectric properties of p-type transparent Sr-doped LaCrO3 thin films has been investigated. For this purpose, high-quality fully strained La0.75Sr0.25CrO3 (LSCO) epitaxial thin films were grown by molecular beam epitaxy on three different (pseudo)cubic (001)-oriented perovskite oxide substrates: LaAlO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, and DyScO3. The lattice mismatch between the LSCO films and the substrates induces in-plane strain ranging from -2.06% (compressive) to +1.75% (tensile). The electric conductivity can be controlled over 2 orders of magnitude, ranging from 0.5 S/cm (tensile strain) to 35 S/cm (compressive strain). Consistently, the Seebeck coefficient S can be finely tuned by a factor of almost 2 from 127 microV/K (compressive strain) to 208 microV/K (tensile strain). Interestingly, we show that the thermoelectric power factor can consequently be tuned by almost 2 orders of magnitude. The compressive strain yields a remarkable enhancement by a factor of 3 for 2% compressive strain with respect to almost relaxed films. These results demonstrate that epitaxial strain is a powerful lever to control the electric properties of LSCO and enhance its thermoelectric properties, which is of high interest for various devices and key applications such as thermal energy harvesters, coolers, transparent conductors, photocatalyzers, and spintronic memories., Comment: Article, 10 pages in final published format, 6 figures

Published
2021
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2. Enhanced ferroelectricity in epitaxial Hf0.5Zr0.5O2 thin films integrated with Si(001) using SrTiO3 templates

Author

Lyu, J., Fina, I., Bachelet, R., Saint-Girons, G., Estandia, S., Gazquez, J., Fontcuberta, J., and Sanchez, F.

Subjects
Physics - Applied Physics, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

SrTiO3 templates have been used to integrate epitaxial bilayers of ferroelectric Hf0.5Zr0.5O2 and La2/3Sr1/3MnO3 bottom electrode on Si(001). The Hf0.5Zr0.5O2 films show enhanced properties in comparison to equivalent films on SrTiO3(001) single crystalline substrates. The films, thinner than 10 nm, have very high remnant polarization of 34 uC/cm2. Hf0.5Zr0.5O2 capacitors at operating voltage of 4 V present long retention time well beyond 10 years and high endurance against fatigue up to 109 cycles. The robust ferroelectric properties displayed by the epitaxial Hf0.5Zr0.5O2 films on Si(001) using SrTiO3 templates paves the way for the monolithic integration on silicon of emerging memory devices based on epitaxial HfO2.

Published
2019
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3. Thermoelectric La-doped SrTiO3 epitaxial layers with single-crystal quality: from nanometer to micrometer and mosaicity effects

Author

Apreutesei, M., Debord, R., Bouras, M., Regreny, P., Botella, C., Benamrouche, A., Carretero-Genevrier, A., Gazquez, J., Grenet, G., Pailhes, S., Saint-Girons, G., and Bachelet, R.

Subjects
Condensed Matter - Materials Science
Abstract

High-quality thermoelectric LaxSr1-xTiO3 (LSTO) layers (here with x = 0.2), with thicknesses ranging from 20 nm to 700 nm, have been epitaxially grown on SrTiO3(001) substrates by enhanced solid-source oxide molecular-beam epitaxy. All films are atomically flat (with rms roughness < 0.2 nm), with low mosaicity (<0.1{\deg}), and present very low electrical resistivity (<5 x 10-4 ohm.cm at room temperature), one order of magnitude lower than commercial Nb-doped SrTiO3 single-crystalline substrate. The conservation of transport properties within this thickness range has been confirmed by thermoelectric measurements where Seebeck coefficients of around -60 microV/K have been found for all films, accordingly. Finally, a correlation is given between the mosaicity and the (thermo)electric properties. These functional LSTO films can be integrated on Si in opto-microelectronic devices as transparent conductor, thermoelectric elements or in non-volatile memory structures.

Published
2017
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12. Epitaxial Zn3N2 thin films by molecular beam epitaxy: Structural, electrical, and optical properties.

Author

John, P., Al Khalfioui, M., Deparis, C., Welk, A., Lichtensteiger, C., Bachelet, R., Saint-Girons, G., Rotella, H., Hugues, M., Grundmann, M., and Zúñiga-Pérez, J.

Subjects
MOLECULAR beam epitaxy, MONOMOLECULAR films, THIN films, OPTICAL properties, HALL effect, CARRIER density, ELECTRON diffraction, ELECTRON mobility
Abstract

Single-crystalline Zn3N2 thin films have been grown on MgO (100) and YSZ (100) substrates by plasma-assisted molecular beam epitaxy. Depending on growth conditions, the film orientation can be tuned from (100) to (111). For each orientation, x-ray diffraction and reflection high-energy electron diffraction are used to determine the epitaxial relationships and to quantify the structural quality. Using high-temperature x-ray diffraction, the Zn3N2 linear thermal expansion coefficient is measured with an average of (1.5 ± 0.1) × 10−5 K−1 in the range of 300–700 K. The Zn3N2 films are found to be systematically n-type and degenerate, with carrier concentrations of 1019–1021 cm−3 and electron mobilities ranging from 4 to 388 cm2 V−1 s−1. Low-temperature Hall effect measurements show that ionized impurity scattering is the main mechanism limiting the mobility. The large carrier densities lead to measured optical bandgaps in the range of 1.05–1.37 eV due to Moss–Burstein band filling, with an extrapolated value of 0.99 eV for actual bandgap energy. [ABSTRACT FROM AUTHOR]

Published
2021
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21. Development of Epitaxial Oxide Ceramics Nanomaterials Based on Chemical Strategies on Semiconductor Platforms

Author

Carretero-Genevrier, A., primary, Bachelet, R., additional, Saint-Girons, G., additional, Moalla, R., additional, Vila-Fungueiriño, J. M., additional, Rivas-Murias, B., additional, Rivadulla, F., additional, Rodriguez-Carvajal, J., additional, Gomez, A., additional, Gazquez, J., additional, Gich, M., additional, and Mestres, N., additional

Published
2016
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28. Epitaxial growth of high- κ oxides on silicon

Author

Merckling, C., Saint-Girons, G., Delhaye, G., Patriarche, G., Largeau, L., Favre-Nicollin, V., El-Kazzi, M., Regreny, P., Vilquin, B., Marty, O., Botella, C., Gendry, M., Grenet, G., Robach, Y., and Hollinger, G.

Published
2008
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35. Assessing the insulating properties of an ultrathin SrTiO3 shell grown around GaAs nanowires with molecular beam epitaxy.

Author

Peric, N, Dursap, T, Becdelievre, J, Berthe, M, Addad, A, Romeo, P Rojo, Bachelet, R, Saint-Girons, G, Lancry, O, Legendre, S, Biadala, L, Penuelas, J, and Grandidier, B

Subjects
MOLECULAR beam epitaxy, NANOWIRES, SCANNING tunneling microscopy, RAMAN microscopy, AUDITING standards, TRANSMISSION electron microscopy
Abstract

We have studied electronic transport in undoped GaAs/SrTiO3 coreâ€"shell nanowires standing on their Si substrate with two-tip scanning tunneling microscopy in ultrahigh vacuum. The resistance profile along the nanowires is proportional to the tip separation with resistances per unit length of a few GΩ/ ÎĽ m. Examination of the different transport pathways parallel to the nanowire growth axis reveals that the measured resistance is consistent with a conduction along the interfacial states at the GaAs{110} sidewalls, the 2 nm thick SrTiO3 shell being as much as resistive, despite oxygen deficient growth conditions. The origin of the shell resistivity is discussed in light of the nanowire analysis with transmission electron microscopy and Raman spectroscopy, providing good grounds for the use of SrTiO3 shells as gate insulators. [ABSTRACT FROM AUTHOR]

Published
2022
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44. Epitaxial manganite freestanding bridges for low power pressure sensors.

Author

Le Bourdais, D., Agnus, G., Maroutian, T., Pillard, V., Aubert, P., Bachelet, R., Saint-Girons, G., Vilquin, B., Lefeuvre, E., and Lecoeur, P.

Subjects
MANGANITE, PRESSURE sensors, STRONTIUM titanate, HEAT transfer, ENERGY consumption, FERROELECTRICITY, FERROMAGNETISM
Abstract

The highly temperature-dependent resistivity of the La2/3Sr1/3MnO3 (LSMO) manganite is taken as an advantage in a pressure sensor design based on the Pirani effect. Thin epitaxial films are grown on silicon substrate thanks to a SrTiO3 buffer layer that allows the fabrication of freestanding bridges by means of clean-room processes. The devices are then heated by Joule effect and their temperature modulated by heat transfer through the surrounding gas. The higher the current flowing in the bridge, the larger the resistance variation with pressure is, due to the Pirani effect. The heating current and device geometry are tuned in order to stay in a monotonous regime, avoiding the change of sign of the LSMO temperature coefficient. A sensitivity increased by a factor of 3 and a power consumption reduced by 5 orders of magnitude are measured by comparing oxide devices with conventional metallic ones of same geometry. [ABSTRACT FROM AUTHOR]

Published
2015
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48. Système d'analyse RHEED adapté au contrôle de la croissance de couches minces d'oxydes fonctionnels et de nanofils III-V

Author

Botella, C., Bouras, M., Dursap, T., Han, D., Vettori, M., Bachelet, R., Penuelas, J., Gendry, Michel, Saint-Girons, G., INL - Hétéroepitaxie et Nanostructures (INL - H&N), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Gendry, Michel

Subjects
[SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics
Abstract

International audience; La diffraction RHEED (Reflection High Energy Electron Diffraction) est la principale technique d'analyse pour suivre en temps réel l'évolution d'une croissance épitaxiale de couches minces réalisée dans un réacteur d'épitaxie par jets moléculaires. Cette technique permet d'obtenir des informations sur l'état de la surface de la couche, sur sa qualité cristalline, son éventuelle relaxation et sur sa vitesse de croissance (mesure des oscillations RHEED. L'équipe Hétérotépitaxie et Nanostructures de l'INL développe une forte activité dans le domaine de la croissance épitaxiale de couches minces d'oxydes fonctionnels de structure pérovskite et de nanofils semi-conducteurs III-V. D'une part, les oxydes fonctionnels sont caractérisés par une vitesse de croissance lente et un signal bruité et, d'autre part, les nanofils III-V nécessitent une analyse des taches de diffraction hors plan. Dans ce contexte, nous avons développé un logiciel permettant d'étudier finement le diagramme de diffraction RHEED de ces matériaux. Ce logiciel permet de suivre les variations d'intensités de la tache spéculaire avec des périodes d'oscillations RHEED inférieures à la seconde et pouvant aller jusqu'à plusieurs heures. Il permet aussi de mesurer avec précision les variations d'intensité de tâches de diffraction et les variations du paramètre de maille (dans le plan ou hors plan). Ainsi, nous avons montré qu'il était possible de contrôler la structure cristalline de nanofils de GaAs autocatalysés, entre une phase Wurtzite et une phase Zinc-Blende, en couplant l'analyse RHEED avec des modulations des flux de Gallium ou d'Arsenic pendant la croissance de ces nanofils.

Published
2018

49. Epitaxial La0.7Sr0.3MnO3 thin films on silicon with excellent magnetic and electric properties by combining physical and chemical methods

Author

Vila-Fungueirino, J.M., Gazquez, J., Magen, C., Saint-Girons, G., Bachelet, R., Carretero-Genevrier, A., Institut d’Electronique et des Systèmes (IES), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Matériaux, MicroCapteurs et Acoustique (M2A), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Fundación ARAID, INL - Hétéroepitaxie et Nanostructures (INL - H&N), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Agence Nationale de la Recherche (France), Ecole Normale Supérieure de Lyon, European Commission, Vila-Fungueiriño, José M. [0000-0002-1839-0495], Magen, Cesar [0000-0002-6761-6171], Bachelet, Romain [0000-0002-2910-0449], Carretero Genevrier, Adrian [0000-0003-0488-9452], Vila-Fungueiriño, José M., Magen, Cesar, Bachelet, Romain, and Carretero Genevrier, Adrian

Subjects
lcsh:Biotechnology, Thin-films, [CHIM.MATE]Chemical Sciences/Material chemistry, Chemical solution deposition, chemical solution deposition, Functional oxides, molecular beam epitaxy, lcsh:TP248.13-248.65, functional oxides, silicon integration, lcsh:TA401-492, lcsh:Materials of engineering and construction. Mechanics of materials, Silicon integration, Molecular beam epitaxy
Abstract

Half-metallic ferromagnetic La0.7Sr0.3MnO3 (LSMO) represents an appealing candidate to be integrated on silicon substrates for technological devices such as sensors, data storage media, IR detectors, and so on. Here, we report high-quality epitaxial LSMO thin films obtained by an original combination of chemical solution deposition (CSD) and molecular beam epitaxy (MBE). A detailed study of the thermal, chemical, and physical compatibility between SrTiO3 (STO)/Si buffer layers and LSMO films, grown by MBE and CSD, respectively, enables a perfect integration of both materials. Importantly, we show a precise control of the coercive field of LSMO films by tuning the mosaicity of the STO/Si buffer layer. These results demonstrate the enormous potential of combining physical and chemical processes for the development of low-cost functional oxide-based devices compatible with the complementary metal oxide semiconductor technology., ACG acknowledges the financial support from the French Agence Nationale pour la Recherche (ANR), project Q-NOSS ANR-16-CE09-0006-01 and École Centrale de Lyon under the BQR 2016 project. The research leading to these results has received funding from the European Union Seventh Framework Program under Grant Agreement 312483 - ESTEEM2 (Integrated Infrastructure Initiative–I3). This project has received funding from the EU‐H2020 research and innovation Program under grant agreement No 654360 having benefitted from the access provided by ICMAB-CSIC in Barcelona within the framework of the NFFA‐Europe Transnational Access Activity. Fruitful discussions with Pr. F. Rivadulla from USC are highly acknowledged. INL authors acknowledge the European Commission for funding the project TIPS (H2020-ICT-02-2014-1-644453). We thank P. Regreny, C. Botella, and J. B. Goure for the MBE technical assistance on the Nanolyon technological platform.

Published
2018
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